5. Propagation Environments

Many environmental factors influence growth and production of nursery plants.
The primary processes affected by environmental factors are photosynthesis and transpiration.
Photosynthesis is the means by which light energy from the sun is converted
into chemical energy in the presence of chlorophyll, the green pigment in leaves. During
photosynthesis, sugars are produced from carbon dioxide from the air and water
from the soil while oxygen is released back into the air. Photosynthesis is
a “leaky” process because, to allow the intake of carbon dioxide, water vapor is lost
through pores, or stomata, on the leaf surfaces. This water loss is called transpiration.
To maximize the photosynthesis necessary for plant growth, growers must reduce the
factors that limit photosynthesis or increase the factors that promote photosynthesis.